src/librustc_trans/trans/cabi_x86_64.rs

   1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // The classification code for the x86_64 ABI is taken from the clay language
  12 // https://github.com/jckarter/clay/blob/master/compiler/src/externals.cpp
  13
  14 #![allow(non_upper_case_globals)]
  15 use self::RegClass::*;
  16
  17 use llvm::{Integer, Pointer, Float, Double};
  18 use llvm::{Struct, Array, Attribute, Vector};
  19 use llvm::{StructRetAttribute, ByValAttribute, ZExtAttribute};
  20 use trans::cabi::{ArgType, FnType};
  21 use trans::context::CrateContext;
  22 use trans::type_::Type;
  23
  24 use std::cmp;
  25 use std::iter::repeat;
  26
  27 #[derive(Clone, Copy, PartialEq)]
  28 enum RegClass {
  29     NoClass,
  30     Int,
  31     SSEFs,
  32     SSEFv,
  33     SSEDs,
  34     SSEDv,
  35     SSEInt(/* bitwidth */ u64),
  36     /// Data that can appear in the upper half of an SSE register.
  37     SSEUp,
  38     X87,
  39     X87Up,
  40     ComplexX87,
  41     Memory
  42 }
  43
  44 trait TypeMethods {
  45     fn is_reg_ty(&self) -> bool;
  46 }
  47
  48 impl TypeMethods for Type {
  49     fn is_reg_ty(&self) -> bool {
  50         match self.kind() {
  51             Integer | Pointer | Float | Double => true,
  52             _ => false
  53         }
  54     }
  55 }
  56
  57 impl RegClass {
  58     fn is_sse(&self) -> bool {
  59         match *self {
  60             SSEFs | SSEFv | SSEDs | SSEDv | SSEInt(_) => true,
  61             _ => false
  62         }
  63     }
  64 }
  65
  66 trait ClassList {
  67     fn is_pass_byval(&self) -> bool;
  68     fn is_ret_bysret(&self) -> bool;
  69 }
  70
  71 impl ClassList for [RegClass] {
  72     fn is_pass_byval(&self) -> bool {
  73         if self.is_empty() { return false; }
  74
  75         let class = self[0];
  76            class == Memory
  77         || class == X87
  78         || class == ComplexX87
  79     }
  80
  81     fn is_ret_bysret(&self) -> bool {
  82         if self.is_empty() { return false; }
  83
  84         self[0] == Memory
  85     }
  86 }
  87
  88 fn classify_ty(ty: Type) -> Vec<RegClass> {
  89     fn align(off: usize, ty: Type) -> usize {
  90         let a = ty_align(ty);
  91         return (off + a - 1) / a * a;
  92     }
  93
  94     fn ty_align(ty: Type) -> usize {
  95         match ty.kind() {
  96             Integer => ((ty.int_width() as usize) + 7) / 8,
  97             Pointer => 8,
  98             Float => 4,
  99             Double => 8,
 100             Struct => {
 101               if ty.is_packed() {
 102                 1
 103               } else {
 104                 let str_tys = ty.field_types();
 105                 str_tys.iter().fold(1, |a, t| cmp::max(a, ty_align(*t)))
 106               }
 107             }
 108             Array => {
 109                 let elt = ty.element_type();
 110                 ty_align(elt)
 111             }
 112             Vector => {
 113                 let len = ty.vector_length();
 114                 let elt = ty.element_type();
 115                 ty_align(elt) * len
 116             }
 117             _ => panic!("ty_align: unhandled type")
 118         }
 119     }
 120
 121     fn ty_size(ty: Type) -> usize {
 122         match ty.kind() {
 123             Integer => (ty.int_width() as usize + 7) / 8,
 124             Pointer => 8,
 125             Float => 4,
 126             Double => 8,
 127             Struct => {
 128                 let str_tys = ty.field_types();
 129                 if ty.is_packed() {
 130                     str_tys.iter().fold(0, |s, t| s + ty_size(*t))
 131                 } else {
 132                     let size = str_tys.iter().fold(0, |s, t| align(s, *t) + ty_size(*t));
 133                     align(size, ty)
 134                 }
 135             }
 136             Array => {
 137                 let len = ty.array_length();
 138                 let elt = ty.element_type();
 139                 let eltsz = ty_size(elt);
 140                 len * eltsz
 141             }
 142             Vector => {
 143                 let len = ty.vector_length();
 144                 let elt = ty.element_type();
 145                 let eltsz = ty_size(elt);
 146                 len * eltsz
 147             }
 148
 149             _ => panic!("ty_size: unhandled type")
 150         }
 151     }
 152
 153     fn all_mem(cls: &mut [RegClass]) {
 154         for elt in cls {
 155             *elt = Memory;
 156         }
 157     }
 158
 159     fn unify(cls: &mut [RegClass],
 160              i: usize,
 161              newv: RegClass) {
 162         if cls[i] == newv { return }
 163
 164         let to_write = match (cls[i], newv) {
 165             (NoClass,     _) => newv,
 166             (_,           NoClass) => return,
 167
 168             (Memory,      _) |
 169             (_,           Memory) => Memory,
 170
 171             (Int,         _) |
 172             (_,           Int) => Int,
 173
 174             (X87,         _) |
 175             (X87Up,       _) |
 176             (ComplexX87,  _) |
 177             (_,           X87) |
 178             (_,           X87Up) |
 179             (_,           ComplexX87) => Memory,
 180
 181             (SSEFv,       SSEUp) |
 182             (SSEFs,       SSEUp) |
 183             (SSEDv,       SSEUp) |
 184             (SSEDs,       SSEUp) |
 185             (SSEInt(_),   SSEUp) => return,
 186
 187             (_,           _) => newv
 188         };
 189         cls[i] = to_write;
 190     }
 191
 192     fn classify_struct(tys: &[Type],
 193                        cls: &mut [RegClass],
 194                        i: usize,
 195                        off: usize,
 196                        packed: bool) {
 197         let mut field_off = off;
 198         for ty in tys {
 199             if !packed {
 200                 field_off = align(field_off, *ty);
 201             }
 202             classify(*ty, cls, i, field_off);
 203             field_off += ty_size(*ty);
 204         }
 205     }
 206
 207     fn classify(ty: Type,
 208                 cls: &mut [RegClass], ix: usize,
 209                 off: usize) {
 210         let t_align = ty_align(ty);
 211         let t_size = ty_size(ty);
 212
 213         let misalign = off % t_align;
 214         if misalign != 0 {
 215             let mut i = off / 8;
 216             let e = (off + t_size + 7) / 8;
 217             while i < e {
 218                 unify(cls, ix + i, Memory);
 219                 i += 1;
 220             }
 221             return;
 222         }
 223
 224         match ty.kind() {
 225             Integer |
 226             Pointer => {
 227                 unify(cls, ix + off / 8, Int);
 228             }
 229             Float => {
 230                 if off % 8 == 4 {
 231                     unify(cls, ix + off / 8, SSEFv);
 232                 } else {
 233                     unify(cls, ix + off / 8, SSEFs);
 234                 }
 235             }
 236             Double => {
 237                 unify(cls, ix + off / 8, SSEDs);
 238             }
 239             Struct => {
 240                 classify_struct(&ty.field_types(), cls, ix, off, ty.is_packed());
 241             }
 242             Array => {
 243                 let len = ty.array_length();
 244                 let elt = ty.element_type();
 245                 let eltsz = ty_size(elt);
 246                 let mut i = 0;
 247                 while i < len {
 248                     classify(elt, cls, ix, off + i * eltsz);
 249                     i += 1;
 250                 }
 251             }
 252             Vector => {
 253                 let len = ty.vector_length();
 254                 let elt = ty.element_type();
 255                 let eltsz = ty_size(elt);
 256                 let mut reg = match elt.kind() {
 257                     Integer => SSEInt(elt.int_width()),
 258                     Float => SSEFv,
 259                     Double => SSEDv,
 260                     _ => panic!("classify: unhandled vector element type")
 261                 };
 262
 263                 let mut i = 0;
 264                 while i < len {
 265                     unify(cls, ix + (off + i * eltsz) / 8, reg);
 266
 267                     // everything after the first one is the upper
 268                     // half of a register.
 269                     reg = SSEUp;
 270                     i += 1;
 271                 }
 272             }
 273             _ => panic!("classify: unhandled type")
 274         }
 275     }
 276
 277     fn fixup(ty: Type, cls: &mut [RegClass]) {
 278         let mut i = 0;
 279         let ty_kind = ty.kind();
 280         let e = cls.len();
 281         if cls.len() > 2 && (ty_kind == Struct || ty_kind == Array || ty_kind == Vector) {
 282             if cls[i].is_sse() {
 283                 i += 1;
 284                 while i < e {
 285                     if cls[i] != SSEUp {
 286                         all_mem(cls);
 287                         return;
 288                     }
 289                     i += 1;
 290                 }
 291             } else {
 292                 all_mem(cls);
 293                 return
 294             }
 295         } else {
 296             while i < e {
 297                 if cls[i] == Memory {
 298                     all_mem(cls);
 299                     return;
 300                 }
 301                 if cls[i] == X87Up {
 302                     // for darwin
 303                     // cls[i] = SSEDs;
 304                     all_mem(cls);
 305                     return;
 306                 }
 307                 if cls[i] == SSEUp {
 308                     cls[i] = SSEDv;
 309                 } else if cls[i].is_sse() {
 310                     i += 1;
 311                     while i != e && cls[i] == SSEUp { i += 1; }
 312                 } else if cls[i] == X87 {
 313                     i += 1;
 314                     while i != e && cls[i] == X87Up { i += 1; }
 315                 } else {
 316                     i += 1;
 317                 }
 318             }
 319         }
 320     }
 321
 322     let words = (ty_size(ty) + 7) / 8;
 323     let mut cls: Vec<_> = repeat(NoClass).take(words).collect();
 324     if words > 4 {
 325         all_mem(&mut cls);
 326         return cls;
 327     }
 328     classify(ty, &mut cls, 0, 0);
 329     fixup(ty, &mut cls);
 330     return cls;
 331 }
 332
 333 fn llreg_ty(ccx: &CrateContext, cls: &[RegClass]) -> Type {
 334     fn llvec_len(cls: &[RegClass]) -> usize {
 335         let mut len = 1;
 336         for c in cls {
 337             if *c != SSEUp {
 338                 break;
 339             }
 340             len += 1;
 341         }
 342         return len;
 343     }
 344
 345     let mut tys = Vec::new();
 346     let mut i = 0;
 347     let e = cls.len();
 348     while i < e {
 349         match cls[i] {
 350             Int => {
 351                 tys.push(Type::i64(ccx));
 352             }
 353             SSEFv | SSEDv | SSEInt(_) => {
 354                 let (elts_per_word, elt_ty) = match cls[i] {
 355                     SSEFv => (2, Type::f32(ccx)),
 356                     SSEDv => (1, Type::f64(ccx)),
 357                     SSEInt(bits) => {
 358                         assert!(bits == 8 || bits == 16 || bits == 32 || bits == 64,
 359                                 "llreg_ty: unsupported SSEInt width {}", bits);
 360                         (64 / bits, Type::ix(ccx, bits))
 361                     }
 362                     _ => unreachable!(),
 363                 };
 364                 let vec_len = llvec_len(&cls[i + 1..]);
 365                 let vec_ty = Type::vector(&elt_ty, vec_len as u64 * elts_per_word);
 366                 tys.push(vec_ty);
 367                 i += vec_len;
 368                 continue;
 369             }
 370             SSEFs => {
 371                 tys.push(Type::f32(ccx));
 372             }
 373             SSEDs => {
 374                 tys.push(Type::f64(ccx));
 375             }
 376             _ => panic!("llregtype: unhandled class")
 377         }
 378         i += 1;
 379     }
 380     if tys.len() == 1 && tys[0].kind() == Vector {
 381         // if the type contains only a vector, pass it as that vector.
 382         tys[0]
 383     } else {
 384         Type::struct_(ccx, &tys, false)
 385     }
 386 }
 387
 388 pub fn compute_abi_info(ccx: &CrateContext,
 389                         atys: &[Type],
 390                         rty: Type,
 391                         ret_def: bool) -> FnType {
 392     fn x86_64_ty<F>(ccx: &CrateContext,
 393                     ty: Type,
 394                     is_mem_cls: F,
 395                     ind_attr: Attribute)
 396                     -> ArgType where
 397         F: FnOnce(&[RegClass]) -> bool,
 398     {
 399         if !ty.is_reg_ty() {
 400             let cls = classify_ty(ty);
 401             if is_mem_cls(&cls) {
 402                 ArgType::indirect(ty, Some(ind_attr))
 403             } else {
 404                 ArgType::direct(ty,
 405                                 Some(llreg_ty(ccx, &cls)),
 406                                 None,
 407                                 None)
 408             }
 409         } else {
 410             let attr = if ty == Type::i1(ccx) { Some(ZExtAttribute) } else { None };
 411             ArgType::direct(ty, None, None, attr)
 412         }
 413     }
 414
 415     let mut arg_tys = Vec::new();
 416     for t in atys {
 417         let ty = x86_64_ty(ccx, *t, |cls| cls.is_pass_byval(), ByValAttribute);
 418         arg_tys.push(ty);
 419     }
 420
 421     let ret_ty = if ret_def {
 422         x86_64_ty(ccx, rty, |cls| cls.is_ret_bysret(), StructRetAttribute)
 423     } else {
 424         ArgType::direct(Type::void(ccx), None, None, None)
 425     };
 426
 427     return FnType {
 428         arg_tys: arg_tys,
 429         ret_ty: ret_ty,
 430     };
 431 }